Khalil Arshak

An overview of foodborne pathogen detection: In the perspective of biosensors

Food safety is a global health goal and the foodborne diseases take a major crisis on health. Therefore, detection of microbial pathogens in food is the solution to the prevention and recognition of problems related to health and safety. For this reason, a comprehensive literature survey has been carried out aiming to give an overview in the field of foodborne pathogen detection. Conventional and standard bacterial detection methods such as culture and colony counting methods, immunology-based methods and polymerase chain reaction based methods, may take up to several hours or even a few days to yield an answer. Obviously this is inadequate, and recently many researchers are focusing towards the progress of rapid methods. Although new technologies like biosensors show potential approaches, further research and development is essential before biosensors become a real and reliable choice. New bio-molecular techniques for food pathogen detection are being developed to improve the biosensor characteristics such as sensitivity and selectivity, also which is rapid, reliable, effective and suitable for in situ analysis. This paper not only offers an overview in the area of microbial pathogen detection but it also describes the conventional methods, analytical techniques and recent developments in food pathogen detection, identification and quantification, with an emphasis on biosensors.

A review of gas sensors employed in electronic nose applications

This paper reviews the range of sensors used in electronic nose (e‐nose) systems to date. It outlines the operating principles and fabrication methods of each sensor type as well as the applications in which the different sensors have been utilised. It also outlines the advantages and disadvantages of each sensor for application in a cost‐effective low‐power handheld e‐nose system.

Review on State-of-the-art in Polymer Based pH Sensors

This paper reviews current state-of-the-art methods of measuring pH levels that are based on polymer materials. These include polymer-coated fibre optic sensors, devices with electrodes modified with pH-sensitive polymers, fluorescent pH indicators, potentiometric pH sensors as well as sensors that use combinatory approach for ion concentration monitoring.

Conducting Polymers and Their Applications to Biosensors: Emphasizing on Foodborne Pathogen Detection

Detection of microbial pathogens in food is the solution to the prevention and recognition of problems related to health and safety. New biomolecular approaches for foodborne pathogen detection are being developed to improve the biosensor characteristics such as sensitivity and selectivity, also which is rapid, reliable, cost-effective, and suitable for in situ analysis. Recently, conducting polymers have drawn attention in the development of biosensors. The electrically conducting polymers have numerous features, which allow them to act as excellent materials for immobilization of biomolecules. Also, their unique properties make them appealing alternatives for specific materials currently employed for the fabrication of biosensors. Therefore, this paper presents a comprehensive literature review detailing the salient features of conducting polymers and their application to biosensors with an emphasis on foodborne pathogen detection.

Review Paper: Materials and Techniques for In Vivo pH Monitoring

Advances in semiconductor sensor technology, medical diagnostics, and health care needs a rapid boost in research into novel miniaturized pH sensors, which can be used in vivo for continuous patient monitoring. Requirements for the in vivo sensor are materials biocompatibility, high measurement precision, a response time of an order of less than seconds, and the possibility of continuous 24-h monitoring. Monitoring of the pH values is important in the study of tissue metabolism, in neurophysiology, cancer diagnostics, and so forth. Muscle pH can be used to triage and help treat trauma victims as well as to indicate poor peripheral blood flow in diabetic patients. Clearly, to avoid infection and spread of diseases, all in vivo monitoring devices should be single-use/disposable, which puts strict requirement on their price. This paper reviews the wide range of methods and materials used for in vivo measurement of pH levels, such as using the optical fibers, pH-sensitive polymers, ion-sensitive field effect transistors, near infrared spectroscopy, nuclear magnetic resonance, and fluorescent pH indicators.

Development of new capacitive strain sensors based on thick film polymer and cermet technologies

Abstract In this work, the strain sensing characteristics of new thick film capacitive sensors are presented. New cermet and polymer dielectric pastes based on lead–zirconate–titanate (PZT) and polyvinylidene fluoride (PVDF) have been developed. The screen printing technique has been used to fabricate the sensors on 96% alumina substrates. Various strain gauge characteristics have been studied, including the electrical properties of both the cermet and polymeric films. Both the cermet and polymer sensors exhibit good dielectric properties with gauge factors comparable to piezoresistive strain sensors. An application circuit based on integrated bipolar arrays incorporating the new capacitive strain sensors was designed and tested. The output from this circuit is a frequency that is proportional to the applied strain.

A Review and Adaptation of Methods of Object Tracking to Telemetry Capsules

Abstract This review considers techniques employing radio frequency (RF) as well as ultrasound signals for tracking. Medical capsules have been employed since the SOs to measure various physiological parameters in the human body. Examples are temperature, pH, or pressure inside the gastrointestinal (GI) tract. The development and subsequent incorporation of new technology into reasonably priced, commercially available devices have made ultrasound and RF devices readily accessible for medical diagnosis. Some applications for telemetry capsules are drug delivery, and collection of tissue/fluid samples. Samples are taken from the GI to understand or treat diseases where diagnosis can only be made by taking a biopsy from the intestinal walls. Such biopsies have traditionally been performed using customized endoscopes. In order for a telemetry capsule to be effective in the above named tasks, accurate knowledge of the location of the capsule within the body during tests is necessary. As such, methods for calcu...

Crystallization effects in oxygen annealed Ta2O5 thin films on Si

Abstract The effect of crystallization after high temperature oxygen annealing of r.f. sputtered Ta 2 O 5 thin films on Si has been investigated. The as-deposited and annealed at 873 K layers are amorphous whereas crystalline, Ta 2 O 5 (orthorombic β-Ta 2 O 5 phase) was obtained after oxygen annealing at 1123 K. The results [electrical, X-ray diffraction (XRD), transmission electron microscopy (TEM)] reveal the formation of an interfacial SiO 2 layer (of approx. 3.5–4.5 nm) under all technological regimes used. The thickness and the quality of this layer depends on the substrate temperature during the deposition and on oxygen annealing. The higher (493 K) substrate temperature stimulates the formation of amorphous rather than crystalline SiO 2 . Electrical characteristics of amorphous and crystalline Ta 2 O 5 thin films have been compared. The oxygen annealing reduces fixed oxide charge and increases breakdown fields. Crystalline Ta 2 O 5 shows better leakage current properties than the amorphous one. Bulk permittivity was found to be (23–27) for amorphous and (32–37) for crystalline Ta 2 O 5 layers, respectively. Evidence exists that amorphous and crystalline Ta 2 O 5 exhibit different conduction mechanisms depending on the electric field.

pH Sensitivity of Novel PANI/PVB/PS3 Composite Films.

This paper reports on the results from the investigation into the pH sensitivity of novel PANI/PVB/PS3 composite films. The conductimetric sensing mode was chosen as it is one of the most promising alternatives to the mainstream pH-sensing methods and it is the least investigated due to the popularity of other approaches. The films were deposited using both screen-printing and a drop-coating method. It was found that the best response to pH was obtained from the screen-printed thick films, which demonstrated a change in conductance by as much as three orders of magnitude over the pH range pH2-pH11. The devices exhibited a stable response over 96 hours of operation. Several films were immersed in buffer solutions of different pH values for 96 hours and these were then investigated using XPS. The resulting N 1s spectra for the various films confirmed that the change in conductance was due to deprotonation of the PANI polymer backbone. SEM and Profilometry were also undertaken and showed that no considerable changes in the morphology of the films took place and that the films did not swell or contract due to exposure to test solutions.

Glucose monitoring using electromagnetic waves and microsensor with interdigitated electrodes

A microscale glucose sensor for biomedical applications was fabricated utilizing the enzyme glucose oxidase and the polymer poly(o-phenylenediamine). A solution containing the enzyme immobilized in the polymer was deposited on interdigitated microelectrodes to form sensor arrays. This was achieved using novel nanopatterning technology offered by BioForce NanoeNabler™. Samples containing different concentrations of glucose were applied to the sensor while the system was being monitored for variances in either current or conductance. The resulting changes in the electrical characteristics of the sensor monitored in real time were found to be proportional to the different concentrations of glucose applied. It is strongly believed that the size reduction of the sensor to a few microns described in this paper creates new opportunities in the areas of chemical and biological sensor development.